TY - JOUR
T1 - Plasmons in layered nanospheres and nanotubes investigated by spatially resolved electron energy-loss spectroscopy
AU - Kociak, M.
AU - Henrard, L.
AU - Stéphan, O.
AU - Suenaga, K.
AU - Colliex, C.
PY - 2000/1/1
Y1 - 2000/1/1
N2 - We present an extensive electron energy loss spectroscopy study of the low-loss energy region, recorded on multishell carbon and boron-nitride nanotubes and carbon hyperfullerenes. Collections of spectra were recorded in a scanning transmission electron microscope by scanning a subnanometer probe from vacuum into the center of the nano-objects. This experimental technique provides the unique ability of disentangling and identifying the different excitation modes of a nanoparticle. We concentrate on the study of surface modes excited in a near-field geometry where the coupling distance between the electron beam and the surface of the nano-objects is accurately monitored. Similarities between surface collective excitations in the different layered nanostructures (cylindrical or spherical, boron nitride, or carbon constituted) are pointed out. Two surface modes at 12-13 eV and 17-18 eV are experimentally clearly evidenced. We show that these modes are accurately described by a classical continuum dielectric model taking fully into account the anisotropic character and the hollow geometry of the nanoparticles. These two modes are shown to be directly related to the in-plane and out-of-plane components of the dielectric tensor. The higher-energy mode (in-plane mode) is shown to shift to higher energy with decreasing impact parameter, as a result of an increase in the weights of the high-order multipolar modes while reaching the surface of the nano-objects.
AB - We present an extensive electron energy loss spectroscopy study of the low-loss energy region, recorded on multishell carbon and boron-nitride nanotubes and carbon hyperfullerenes. Collections of spectra were recorded in a scanning transmission electron microscope by scanning a subnanometer probe from vacuum into the center of the nano-objects. This experimental technique provides the unique ability of disentangling and identifying the different excitation modes of a nanoparticle. We concentrate on the study of surface modes excited in a near-field geometry where the coupling distance between the electron beam and the surface of the nano-objects is accurately monitored. Similarities between surface collective excitations in the different layered nanostructures (cylindrical or spherical, boron nitride, or carbon constituted) are pointed out. Two surface modes at 12-13 eV and 17-18 eV are experimentally clearly evidenced. We show that these modes are accurately described by a classical continuum dielectric model taking fully into account the anisotropic character and the hollow geometry of the nanoparticles. These two modes are shown to be directly related to the in-plane and out-of-plane components of the dielectric tensor. The higher-energy mode (in-plane mode) is shown to shift to higher energy with decreasing impact parameter, as a result of an increase in the weights of the high-order multipolar modes while reaching the surface of the nano-objects.
UR - http://www.scopus.com/inward/record.url?scp=0001720486&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.61.13936
DO - 10.1103/PhysRevB.61.13936
M3 - Article
AN - SCOPUS:0001720486
SN - 1098-0121
VL - 61
SP - 13936
EP - 13944
JO - Physical Review. B, Condensed Matter and Materials Physics
JF - Physical Review. B, Condensed Matter and Materials Physics
IS - 20
ER -